The present invention relates generally to the field of image displays and, more specifically, to image displays which permit the simultaneous viewing of both an electronic image and of the outside environment.
It is often desirable to be able to view an electronic image, such as a television picture or a computer display in a private, confidential manner. Typically this requires that the viewer be placed within the same enclosure as the imaging device, typically a cathode ray tube or a flat panel display. However, this limits both the mobility and safety of the viewer because he is unable to monitor the outside environment at the same time. With advances in very large scale integrated circuits and miniature imaging systems, it is now possible to place an entire television within an enclosure the size of a helmet or goggles. While this allows increased mobility, it endangers the wearer by cutting him off from external visual stimuli.
A.N. Stanton (U.S. Pat. No. 3,059,519) presents a headgear mounted cathode ray tube and binocular viewing device which allows for simultaneous viewing of an external image and an electronic image, however, this device does not allow the user to balance the relative light levels of the images. When the external light level falls, the external image is washed out by the electronic image. When the external light level increases, the electronic image is washed out. J. L. Jones (U.S. Pat. No. 3,670,097) provides a stereoscopic television system which provides a stereoscopic electronic image but does not provide a direct view of the external environment and is, therefore, not within the scope of the present invention.